1. (Field of the Invention)
The present invention relates to a Y2O3 sintered material, a corrosion resistant member and a method for manufacturing the same, and members of a semiconductor/liquid crystal manufacturing apparatus. The Y2O3 sintered material and the corrosion resistant member of the present invention are particularly suitable for members of a semiconductor/liquid crystal manufacturing apparatus that are required to have high resistance against corrosion by corrosive gases or plasma thereof, such as chamber, microwave introducing window, shower head, focus ring, shield ring or the like.
2. (Description of the Related Art)
In recent years, plasma treatment technology has been widely employed in etching, film deposition and other processes of manufacturing semiconductor or liquid crystal devices. Such processes utilize much corrosive gases that have reactive power such as those based on fluorine, chlorine or other halogen element. Accordingly, members of the semiconductor/liquid crystal manufacturing apparatus that are exposed to corrosive gas or plasma thereof are required to have high corrosion resistance.
In the prior art, such corrosion resistant members have been formed from quartz glass or corrosion resistant metals such as stainless steel and aluminum.
In addition to the above, ceramic materials have also been used to form the corrosion resistant member, such as sintered alumina, sintered aluminum nitride, or such sintered ceramic material coated with another ceramics such as silicon carbide.
More recently, instead of the ceramics described above, use of highly corrosion resistant materials such as sintered yttrium aluminum garnet (YAG) and Y2O3 sintered material to form the corrosion resistant member has come to be viewed as very promising.
Y2O3 sintered material, in particular, is regarded as excellent in corrosion resistance for the reasons described below. The Y2O3 sintered material, when Y2O3 included therein is exposed to a corrosive gas that contains a halogen element such as fluorine-based gas, yields products consisting mainly of YF3. For example, reaction of chlorine-based gas and Y2O3 results in products consisting mainly of YCl3. These reaction products have melting points (YF3: 1152° C., YCl3: 680° C.) that are higher than those of reaction products generated through reaction of the gas with quartz glass or sintered aluminum oxide that has been used in the prior art (−90° C. of SiF4 or 1040° C. of AlF3 in the case of fluorine-based gas, −70° C. of SiCl4 or 178° C. of AlCl3 in the case of chlorine-based gas,). Since the reaction products (YF3, YCl3) have high melting points, Y2O3 sintered material resists corrosion even when exposed to plasma of corrosive gas at a high temperature.
Technologies applied to members made of Y2O3 sintered material subjected to exposure to corrosive gas containing a halogen element and/or plasma thereof are disclosed in patent documents 1 through 8.
Patent Document 1 (Japanese Unexamined Patent Publication (Kokai) No. 2001-139365) describes the use of a sintered ceramic material that contains an oxide of rare earth element and has thermal conductivity of 40 W/m·K or less and total radiation ratio of 80% or less in a temperature range from the room temperature to 500° C.
Patent Document 2 (Japanese Unexamined Patent Publication (Kokai) No. 2001-179080) describes a member for substrate processing of low metal contamination made of Y2O3 having relative density of 94% or higher and purity of 99.5% or higher.
Patent Document 3 (Japanese Unexamined Patent Publication (Kokai) No. 2001-181024) describes a ceramic member that contains 30% by weight or more Y2O3 and has void ratio higher than 3% and not higher than 8%.
Patent Document 4 (Japanese Unexamined Patent Publication (Kokai) No. 2002-68838) describes a plasma-resistant member characterized in that at least surface region thereof is made of Y2O3 sintered material.
Patent Document 5 (Japanese Unexamined Patent Publication (Kokai) No. 2002-255647) describes a Y2O3 sintered material having contents of trace metallic components containing 200 ppm or less Si, 100 ppm or less Al and 200 ppm or less in total of Na, K, Ti, Cr. Fe and Ni in terms of concentration by weight.
Patent Document 6 (Japanese Unexamined Patent Publication (Kokai) No. 2003-55050) describes a Y2O3 sintered material having contents of trace metallic components containing 400 ppm or less Si and 200 ppm or less Al in terms of concentration by weight, wherein mean grain size is 200 μm or less and void ratio is 5% or less.
Patent Document 7 (Japanese Unexamined Patent Publication (Kokai) No. 2001-181042) describes a Y2O3 sintered material made of Y2O3 having relative density of 96% or higher.
Patent Document 8 (Japanese Unexamined Patent Publication (Kokai) No. 5-330911) describes a Y2O3 matrix made by adding titanium oxide or the like to Y2O3.